A fuel cell capable of generating electric power with high efficiency even if the fuel cell is small has been developed as an electric power generator of a distributed energy supply source. However, systems for supplying a hydrogen gas used as fuel during this electric power generation is not developed as a common infrastructure. Therefore, for example, a hydrogen generator which generates a hydrogen-containing gas from a raw material obtained from an existing fossil material infrastructure, such as city gas or LPG, is disposed with the fuel cell. In many cases, the hydrogen generator includes: a reformer which causes a reforming reaction between the raw material and water; a shifter which causes a water gas shift reaction between carbon monoxide and steam in order to reduce the concentration of the carbon monoxide in the hydrogen-containing gas; and a CO remover which oxidizes the carbon monoxide mainly by an oxidizing agent, such as a slight amount of air. Moreover, catalysts suitable for respective reactions are used in respective reaction portions, i.e., for example, a Ru catalyst or a Ni catalyst is used in the reformer, a Cu−Zn catalyst is used in the shifter, and a Ru catalyst or the like is used in the CO remover.
In order to detect leakage of the raw material from a pipe and the like, a sulfur compound based odorant is added to the city gas or the LPG which is the above existing infrastructure. Since the sulfur compound based odorant is a component which poisons the catalyst used in the hydrogen generator, it is common to dispose the desulfurizer, which removes the odorant, in the hydrogen generator in advance.
For example, a method for removing the sulfur compound in the raw material by an adsorptive desulfurizer which uses a zeolite based adsorptive desulfurizing agent has been devised (see Patent Document 1 for example).
Moreover, since the adsorptive desulfurizer can remove by adsorption the sulfur compound at normal temperature, it excels in a start-up property of the hydrogen generator as compared to a hydro-desulfurizer. However, the sulfur compound in the raw material is supplied at all times, and an adsorptive desulfurization performance of the desulfurizer deteriorates when the period of use of the desulfurizer becomes long. To be specific, since the adsorptive desulfurization performance (adsorption capacity) of the desulfurizer is limited, the desulfurizer needs to be replaced when using it for a long period of time. Here, a desulfurizer having an indicator function capable of easily determining when to replace the desulfurizer has been proposed (see Patent Document 2 for example).
Moreover, the hydrogen generator typically includes a combustor capable of increasing the temperature of the catalyst in a reformer to a level suitable for a catalytic reaction. In a start-up operation of the hydrogen generator, the inside of the reformer is purged by the raw material supplied from a raw material infrastructure and passed through the desulfurizer, and the combustion of the combustor is carried out by using the raw material after the purge (see Patent Document 3 for example).    Patent Document 1: Japanese Laid-Open Patent Application Publication 2004-228016    Patent Document 2: Japanese Laid-Open Patent Application Publication 2002-358992    Patent Document 3: Japanese Laid-Open Patent Application Publication 2005-206395